Regression of Local and Distant Tumor Growth by Tissue Expansion: An Experimental Study of Mammary Carcinoma 13762 in Rats

Soft-tissue expansion is most often used to correct a preexisting deformity or tissue deficit. More recently, tissue expansion has been used prior to creation of the tissue defect to facilitate closure of large defects with better cosmetic results, e.g., free-flap donor sites. Surgical excision of some malignant skin lesions results in difficult-to-close skin defects. Can a soft-tissue expander be used directly beneath a tumor prior to excision? If so, what effect does the tissue expansion have on tumor growth? To study this in the experimental animal, Fischer rats were injected intradermally with 13762 mammary carcinoma cells and assigned at random to one of four groups: group I (n = 24), nonoperated control; group II (n = 22), creation of a sham pocket beneath the tumor group III (n = 21), expander placed beneath the tumor bed, unexpanded; and group IV (n = 22), a tissue expander placed beneath the tumor bed, expanded. Three weeks following injection, the tumors were excised and weighed, and animals were sacrificed and autopsied. Tumor weights in various groups were as follows: group 1, 8.73 ω 1.2 gm; group II, 9.51 ω 1.3 gm; group III, 1.91 ω 0.4 gm; and group IV, 0.83 ω 0.2 gm. The tumor weight of the control (group I) and sham (group II) animals was greater than in the nonexpanded (group III) and expanded (group IV) animals (p < 0.0001). Thirteen of 24 animals (54 percent) in group I, 9 of 22 (41 percent) in group II, 5 of 21 (24 percent) in group III, and 2 of 22 (9 percent) in group IV demonstrated visceral metastases. We conclude that growth of the intradermal 13762 breast tumor in Fischer rats is substantially retarded by placement of a tissue expander beneath the tumor, and this is further diminished by tissue expansion. The tissue expander, in addition, acts as a barrier to visceral spread.